(Beyond Pesticides, October 18, 2023) A meta-analysis published in Toxics finds an association between exposure to organophosphate pesticides (OPs) and respiratory diseases and diabetes mellitus (DM). Specifically, wheezing and asthma are the most common respiratory manifestations of OP exposure, while fluctuation in weight and fat/glucose levels are the most common metabolically related manifestations. Organophosphorus pesticides have a wide range of biological usesâ€”from insecticides to flame retardantsâ€”that make these chemicals ubiquitous, significantly contributing to ecosystem contamination. Thus, OP compounds have a global distribution, with evaporation and precipitation facilitating long-range atmospheric transport, deposition, and bioaccumulation of hazardous chemicals in the environment. Many studies show OPs areÂ highly toxic, and residues areÂ consistently presentÂ in human and animal urine, blood, tissues, and milk. ConsideringÂ 90 percentÂ of Americans have at least one pesticide compound in their body, primarily stemming from dietary exposure, includingÂ foodÂ andÂ drinking water, advocates maintain that current restrictions on their use must adequately detect and assess total chemical contaminants.Â
This study investigated the effects and possible mechanisms involved in adverse health outcomes associated with OP exposure. Reviewing studies from Web of Science, PubMed, Embase, OVID, and the Cochrane Library, researchers systematically searched for articles on OP exposure and respiratory, DM, and cardiovascular disease (CVD) outcomes until 2022. After filtering through relevant analyses, 19 remaining observational studies examined the associations between OP exposure and respiratory diseases, DM, and CVD among the general population or occupational populations. There is also a significant association between OP exposure and DM. However, the study finds little association between OP exposure and CVD, which is not concurrent with other CVD and OP exposure pattern results.
Organophosphate insecticide use is widespread, while industry promotes the chemicals as having greater efficiency and lesser environmental persistence. However, OPs originate from the same compounds as World War IIÂ nerve agents, producing adverse effects on the nervous system, endocrine disruption, reproductive dysfunction, fetal defects, neurotoxic damage, and kidney/liver damage. Chemical exposure can causeÂ a buildup of acetylcholine (a chemical neurotransmitter responsible for brain and muscle function), leading toÂ acute impacts, such as uncontrolled, rapid twitching of some muscles, paralyzed breathing, convulsions, and, in extreme cases, death. Compromised nerve impulse transmission can have broad systemic impacts on the function of multiple body systems. In addition to being highly toxic to terrestrial and aquatic organisms, human exposure toÂ organophosphatesÂ can induce endocrine disruption, reproductive dysfunction, fetal defects, neurotoxic damage, and kidney/liver damage. Exposure can increase vulnerability to deadly diseases, includingÂ COVID-19.Â Moreover, OPs are one of the leading causes ofÂ intentional poisoningÂ globally, as pesticide toxicity makes them potentially lethal substances.
With the aggregate risk standards of pesticides with a common mechanism of toxicity under the Food Quality Protection Act of 1996, the Environmental Protection Agency (EPA) has been forced to remove from the market residential uses of organophosphate pesticides in order to retain agricultural uses. For example, while the residential use of chlorpyrifos was first taken off the market in 1990, it was not until 2022 that agricultural uses were removed following findings of adverse impacts on childrenâ€™s brains and court action. Although most OP uses in the U.S. are now agricultural,Â toxicity expertsÂ recommend banning all OPs for agricultural use. EPA and World Health Organization (WHO) consider overÂ 40Â OPs that are moderately or highly hazardous to human health. EPA classifies some commonly used OPs like malathion, a popular mosquito control, and tetrachlorvinphos, a common flea and tick killer in pet collars and shampoos, as probable carcinogens. Despite this designation and other notorious toxicological concerns, OPs remain in use across the globe.
Despite the lack of studies in this review providing a link between OPs and CVD, studies outside of this review, in fact, find a link between metabolic-mediated CVD. Overall, OP compounds are immunotoxicants (toxic to the immune system), causing injury and alterations to various cells within the body. Additionally, these compounds lower antibody concentration and reduce autoimmune response to stimuli. The review finds current OPs, including chlorpyrifos and malathion, induce oxidative stress, DNA, and cellular damage in the cardiovascular system. Moreover, OPs can disrupt the homeostasis of proinflammatory and anti-inflammatory responses of cytokine proteins responsible for immune protection. Thus, exposure can increase vulnerability to deadly diseases, including cardiovascular disease.
Concerning diabetes, the study suggests OPs could cause an excessive increase in body weight, impaired leptin (the protein that alerts the brain when there is enough fat stored, playing a role in body weight regulation) production, and fat and glucose dysregulation–all common precursors for diabetes, obesity, and other metabolic disorders. Additionally, the generation of reactive oxygen species (ROS) by OPs could also mediate insulin resistance.
This review highlights respiratory diseases as one of OP exposure’s most prominent adverse outcomes. The respiratory system is essential to human survival, regulating gas exchange (oxygen-carbon dioxide) in the body to balance acid and base tissue cells for normal function. However, OPs like chlorpyrifos, malathion, and diazinon can heavily influence the respiratory system asÂ studiesÂ link pesticide use and residue to various respiratory illnesses. The compromise of nerve impulse transmission can have broad systemic impacts on the function of multiple body systems. Damage to the respiratory system can cause many issuesâ€”from asthma and bronchitis to oxidative stress that triggers the development ofÂ extra-respiratory, systemic manifestationsÂ likeÂ rheumatoid arthritisÂ andÂ cardiovascular disease. However, as this review demonstrates, the respiratory system is far from the only bodily system affected by chemical exposure. Furthermore, underlying medical conditions (i.e., heart/kidney disease, diabetes, cancer, high blood pressure, obesity, etc.)Â heighten risksÂ associated with severe illness from disease.Â Therefore, the rise in respiratory infections and organophosphate use over the lastÂ three decadesÂ is highly concerning, especially as research fails to identify an exact cause for the increase in respiratory disease cases.
Replacing dietary exposure to food grown in chemical-intensive agriculture with organicÂ consistently reduces pesticide levels in oneâ€™s body. Preventive practices like organic can eliminate exposure to toxic metabolic disrupting pesticides. There is an indication that maintaining lower levels of conventional, synthetic pesticides is likely toÂ reduce the risk of developing chronic diseases like type 2 diabetes. In addition to positive impacts on the humanÂ microbiome,Â organically grown foodÂ (i.e.,Â milk,Â meat,Â strawberries,Â tomatoes, and aÂ range of other foods) contain a much more diverse bacterial community than their chemically grown counterparts.
Organic agriculture represents a safer, healthier approach to crop production that does not necessitate toxic pesticide use. Beyond Pesticides encourages farmers to embrace and consumers to supportÂ regenerative organicÂ practices. A complement to buying organic is contactingÂ various organic farming organizationsÂ to learn more about what you can do. Understanding the risk of pesticide exposure in disease development is essential since these chemicals can cause disproportionate health effects on individuals working in occupations like firefighters, farmworkers, and landscapers. With too many diseases in the U.S. associated with pesticide exposure, reducing pesticide use is critical to safeguarding public health and addressing cost burdens for local communities. Policies should enforce stricter pesticide regulations and increase research on the long-term impacts of pesticide exposure.Â Beyond Pesticides tracks the most recent health studies on pesticide exposure through ourÂ Pesticide-Induced Diseases Database (PIDD). This database supports the clear need for strategic action to shift away from pesticide dependency. For more information on the multiple harms of pesticide exposure, see PIDD pages onÂ asthma/respiratory effects, Â cardiovascular disease, Â diabetes,Â obesity, and other diseases.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.